This invention relates to an electric lamp with heat resistant shade.
In case of different lamps mounted with electric burner, a glass reflector structure is used, in which the light-directing feature is provided for by a side-wall of the reflector covered by a metallic layer. The glass side-wall of the reflector ends in a plane or convex front wall, in other words the reflector has a lens for emitting the light beam. The glass reflector constitutes a rigid, fragile structure.
U.S. Pat. No. 4,548,589 discloses a halogen bulb lamp assembly manufactured by mounting a previously aligned halogen bulb unit in a one-piece molded plastic rectangular reflector with a mirrorized paraboloidal inner surface. The halogen bulb unit has a pair of spaced connector pins that are coated with an epoxy adhesive and inserted into a pair of stepped through bores in the reflector. This construction uses plastic that is less fragile, however, the molding procedure is an expensive technology when shapes following different demands are quickly changed.
If the radiation flux at the reflecting wall is high, the thermal load of the plastic wall is considerable and the danger of softening may occur. U.S. Pat. No. 4,380,794 discloses a surgical lamp including a thermoplastic reflector, which reflects visible light but passes infrared radiation. The reflector is fabricated from molded polyetherimide plastic resin. A dichroic coating is vacuum deposited directly upon the front surface of the reflector. This reflector eliminates the excess thermal load, but the quite large plastic reflector element can easily be damaged. The molding technology of the reflector makes also this construction expensive as well.
Thus there is a particular need for a lamp with an easily variable and still not expensive element of directing light. There is also a need for a lamp with a unit of directing light, which is not fragile and not sensitive to mechanical damages, such as, for example, unintentional dropping. It is also desirable that the lamp can be manufactured easily.